The present disclosure relates generally to similar user identifiers.
From a content provider's perspective, content such as an advertisement placed on a web page may or may not be of interest or useful for the end users viewing the web page. In some systems, the content of a web page may be used to help select more relevant content to be provided with the web page. For example, a retailer or manufacturer selling golf clubs may place content on a website devoted to golf, since visitors to the website may share a common interest in golf. Such systems may use keywords located in the text of the website to identify topics discussed on the website.